Coating nozzles are known for the coating and consolidating or fixing of flat material webs, for example flat carbon fibers or carbon filaments running next to one another. These coating nozzles, often also referred to as pultrusion nozzles, serve for applying a hot coating liquid, which wets the fibers and flows between the fibers. Upon further guiding the flat material web through an oven, the coating liquid cools off, whereby the fibers are permanently adhesively bonded with one another and thereby a consolidated tape is obtained. This can then be rolled up and used in a later process for the production of light structural components.
The known coating nozzles comprise flexible, heatable supply lines, which consist of plastic, and through which molten coating material can be guided or fed. The use of flexible supply lines is necessary in order to be able to open and clean the nozzle during the production with only short standstill times, because during the impregnation, it often gives rise to the poking-up or jamming of damaged fibers, which then accumulate in the coating nozzle or nozzles. With the use of rigid lines, a simple opening for the purpose of cleaning is not possible.
The plastic supply lines on the one hand must withstand high pressures and on the other hand must ideally withstand high melt temperatures. In consideration of both of these points, however, the plastic supply lines are not optimal. For example, generally they can withstand only a melt temperature of up to 260° C. Thermoplastics such as e.g. PA6, PET etc. with higher melt temperatures and required processing pressures are therefore not usable. Additionally it is a factor that the part of the flexible supply line that feeds or guides the melt is not smooth but rather wavy. This leads to very greatly varying dwell times or residence times of the melt in the supply line, which leads to a very strong thermal breakdown or decomposition of parts of the melt.